All-wheel drive capable vehicles have many advantages over vehicles having a driveline connected to only a single axle. Specifically, all-wheel drive capable vehicles have increased traction and enhanced drivability over similar vehicles that are driven using only a single axle.
However, traditional all-wheel drive vehicles are disadvantaged by requiring continuous rotation of a second drive axle, and other portions of the driveline, at road speed, even when the all-wheel drive functionality is not beneficial. Consequently, traditional all-wheel drive vehicles tend to have reduced fuel, and overall, efficiency when compared to vehicles having only a single drive axle.
All-wheel drive vehicles incorporating a secondary driveline disconnect feature are being developed. In such vehicles, when a control system detects that all-wheel drive functionality is not required, the control system disconnects the second drive axle (and other associated driveline components) to place the driveline into a single axle drive mode. Once the second drive axle is disconnected, there is no transfer of torque to the second drive axle. As a result, speed-dependent losses associated with the second drive axle (and other associated driveline components) are eliminated by allowing the second drive axle (and other associated driveline components) to remain in an idle condition.
Secondary driveline disconnect systems may utilize an electromagnetic actuator to perform an engagement and a disengagement of the secondary driveline. Remanent magnetization may be utilized to place the electromagnetic actuator in a stable state without the application of current thereto. However, removing the remanent magnetization in a consistent and predictable manner using conventional methods may be affected by many operational variables, such as but not limited to, temperature, manufacturing tolerances, and part variation.
The disclosure herein describes a method and system for consistently and efficiently connecting and disconnecting an electromagnetic actuator.